Field
Embodiments of the present disclosure generally relate to methods for conditioning remote plasma source.
Description of the Related Art
Plasma-enhanced chemical vapor deposition (PECVD) process is a process where electromagnetic energy is applied to at least one precursor gas or vapor to transform the precursor into a reactive plasma. Forming a plasma can lower the temperature required to form a film, increase the rate of formation, or both. Plasma may be generated inside the processing chamber, i.e., in situ, or in a remote plasma generator that is remotely positioned from the processing chamber. Remote plasma generators offer several advantages. For example, the remote plasma generator provides a plasma capability to a deposition system that does not have an in situ plasma system. The use of the remote plasma generator also minimizes the plasma interaction with the substrate and chamber components, thereby preventing the interior of the processing chamber from undesirable by-products of the plasma formation process.
Remote plasma generators generally have a protective anodized aluminum coating to protect the aluminum interior walls from degradation. However, anodized aluminum coatings are usually porous and prone to surface reactions. Therefore, the lifetime of anodized aluminum coatings is limited due to the degradation of the anodized coating in the plasma cleaning environment. Failure of the protective anodized coating over an aluminum surface leads to excessive particulate generation within the downstream reactor chamber. In addition, the downstream reactor chamber also suffers unstable plasma performance due to change in surface condition of the protective anodized coating as the process continues. Therefore, the wafer deposition/etch rates, film uniformity and plasma coupling efficiency from wafer to wafer are degraded.
While a frequent chamber cleaning may be performed to stabilize the chamber conditions, the chamber cleaning chemistries such as NF3 will degrade the anodized coating to degrade at much faster rate. In some cases where the remote plasma source uses an AlN plasma block or anodized plasma block, the surface condition inside the remote plasma source will change over time with deposition or clean chemistries. This change in surface condition of the plasma block does not provide repeatable plasma performance resulting in inconsistent wafer-to-wafer performance over time.
Therefore, there is a need for methods for conditioning the surface of the remote plasma generator to provide stable and repeatable plasma performance while maintaining the substrate throughput.